Warped guitar necks: Part 3 - Defining things and Bow
I kicked off a discussion on warped necks by talking about what a warped neck is not. I suppose, after that, I should really talk about what a warped neck is.
But there’s a problem. I can’t actually give you one single definition.
‘Warped neck’ is too much of a blanket term. At a minimum, it’s too broad and, at most, it’s lost all utility altogether.
So, what I’ll do is take a look at the possible ways in which a guitar or bass neck might ‘warp’. Then, each of those differently types of warp can be discussed.
Actually, before we even get to that, let’s start with trying to define the word itself. In this context, ‘warp’ means some unwanted deformation in a neck — whether through bending, twisting, or shearing. This covers a lot of ground so let’s get started.
Up-Bow or Relief
This is the most common ‘deformation’ of a guitar or bass neck. String tension pulls on the neck and forces it into a bow shape.
Most guitar and bass necks will probably have some small amount of bow in them all the time. That’s actually a good thing — most players’ styles will benefit from just a little up-bow. We call this neck bow ‘relief’.
Modern instruments generally have the advantage of an adjustable truss rod that allows us to counter-balance the strings’ pull and control the amount of relief in the neck.
Some instruments, mainly vintage examples, may not have an adjustable truss rod and may rely on some other method to provide passive strengthening against string tension. This is typically a rod or beam of stronger material, inlaid in the neck, beneath the fingerboard.
It’s not unusual for some of these guitar necks to get pulled into an up-bow that’s too extreme for comfortable playing.
Potential fixes
There are a few options we can consider.
Heat-treatment
So, we have to mention the heat-treatment option discussed last time. It’s definitely on the menu of possible solutions but it comes with its own caveats. Have a re-read of the last article on heat-treating necks for more context.
Levelling
Other potential fixes revolve around fret and fingerboard work. If we can 'level’ the fingerboard and/or frets, we can remove some or all of the bow.
For relatively minor bows, it might be possible to level just the frets and give a straighter plane along their tops. Most of the time we’re considering this sort of repair, however, the bow is too big to deal with only in frets.
Removing the frets and levelling the wood of the fingerboard is the next logical step. This might get you where you need to be (and remember that you might not desire a perfectly straight neck at the end of this process — a little relief is usually just fine). Using something like the Erlewine Neck Jig to hold a guitar neck in a particular position while you level the fingerboard can give great results.
There are some considerations, of course. You have to be cautious about how much wood you’ll remove from the fingerboard. You don’t want to end up with a fingerboard tapering down to nothing at one end. Fret slots will likely need to be made deeper in places after you’ve levelled and you may have to replace (or remove and reinstall) inlay.
Corrective refret
Careful refretting, using fret wire with a selection of wider tangs can be a big help in correcting this sort of up-bow. I’ve talked about this sort of corrective compression refret before and you can check that out for more info. The short version is, wider fret wire tangs forced into narrow fret slots can force the neck back against the up-bow.
Much of the time we’ll end up using a combination of a corrective refret and the levelling techniques above to straighten out a neck.
More extreme cases
In some cases, we might apply the levelling technique to the neck itself. The fingerboard is removed and the neck is fully or partially levelled. We may follow with some additional levelling on the reattached fingerboard and even some corrective refretting.
The cons of this are that it’s much more work and therefore more expensive. Levelling on the neck can also alter the shape very slightly and require work to ‘blend’ the edge of the fingerboard back in (more on this next time as this is running long). You’ll likely have some finish touch-up required.
One big pro in this operation is that, with access to the ‘internals’ of the neck you can choose to add some reinforcement against re-bowing in the future. Whether that be a stronger truss rod (adjustable or static) or something like carbon fibre beams, you can do a lot to strengthen a neck here.
Adjustable truss rods aren’t a guarantee
It’s definitely worth mentioning that even instruments with adjustable truss rods can sometimes pull into too much relief — more than the truss rod can correct.
While the fixes described above are all valid in these cases too, before setting off down that road, it’s worth trying to ‘help’ the truss rod do its job.
By forcing the neck into a straighter (or even back-bowed) position using clamps and a beam/level it’s often possible to then tighten up the truss rod in order to keep it in this position. You’re helping the truss rod by doing the actual neck bending/correction so that little adjustment nut doesn’t have to do all the work. Once it’s snug, the job of keeping the neck there is relatively more easy.
Even in the absence of some clamps and tools, you could have a friend hold an instrument on the edge of a counter while you apply some downward force at the headstock to straighten it somewhat.
By the way, all of this should be performed with slack (or removed) strings — don’t fight things more than you need. And, is it necessary for me to tell you to be careful and take no risks you don’t feel comfortable with? There is a potential to damage your guitar here so I’ll state the obvious: Be careful. Take the guitar to a trusted repairer if you’re not sure about anything.
So, like I said, this is starting to get long. I’ll split out the remaining neck warp issues and discuss them over the next week or two.
This article written by Gerry Hayes and first published at hazeguitars.com
